It is a century or a centennial
A 250-year anniversary is called a semiquincentennial. This term combines "semi," meaning half, and "quincentennial," which refers to a 500-year celebration. Thus, a semiquincentennial marks a quarter of a millennium.
A 175-year celebration is typically referred to as a "175th anniversary" or "175th celebration." Such milestones often involve special events or commemorative activities to honor the history and achievements of the organization or entity being celebrated. In some contexts, it might also be informally called a "quasquicentennial," though this term is more commonly used for 125 years.
A period of 100 years is called a century.
The year 1013 AD.
An 150 year celebration is called a Sesquicentennial celebration
An 150 year celebration is called a Sesquicentennial celebration
It is called a "centennial celebration"
A 100 year celebration is called a centennial celebration.
60 year celebration
55th wedding celebration is Emerald.
Centennial
It is called Centenary.
An Emerald anniversary
Diamond Jubilee
Diamond Jubilee
It is a century or a centennial